Question: Xiang needs to print T-shirts for a class project. For what number of shirts will the cost under Plan A and Plan B be the same? \begin{tabular}{lcc} & Plan A & Plan B \\ \hline Set-up charge & \$250 & \$150 \\ Printing charge per shirt & \$4.25 & \$5.25 \\ \end{tabular}
Explanation: Let $x$ be the number of shirts needed for the cost under Plan A to equal the cost under Plan B. We thus have the equation \begin{align*} 250 + 4.25x &= 150 + 5.25x \\ (250-150) &= (5.25 - 4.25)x \\ 100 &= x \end{align*} for an answer of $\boxed{100}\text{ shirts}$.